The present invention relates to the general field of turbines of a turbomachine, and especially of the low-pressure turbine. It also relates more precisely to a device for protecting the rotors of a turbine against the risks of an oil fire.
The low-pressure shaft of a turbomachine drives in rotation the different stages of the low-pressure turbine by means of a journal fixed on the low-pressure shaft. This journal delimits upstream an inner upstream cavity in which air travels intended to ventilate the different discs of the low-pressure turbine arranged downstream from this journal.
To this end, the journal of the low-pressure shaft has ventilation holes enabling ventilation air taken upstream in the motor to feed an outer downstream cavity by transiting via an inner upstream cavity. This ventilation air is then guided towards the discs of the different stages of the low-pressure turbine downstream of the journal to cool them.
Also, it is possible for oil originating from leaks of the lubrication circuit and oil containers of the turbomachine to also be present in the inner upstream cavity of the low-pressure turbine. This oil tends to mix with the ventilation air and borrow the same path as the latter, to end up in the downstream cavity of the low-pressure turbine.
The environment of this downstream cavity is relatively hot, which can cause an oil fire in this cavity with all the harmful consequences this could engender.